


Full Moon

by SinningfortheWinning



Category: Gravity Falls
Genre: Bestiality, Come Inflation, F/M, Forced Pregnancy, Knotting, Rape/Non-con Elements, Sibling Incest, Werewolf Dipper Pines
Language: English
Status: Completed
Published: 2020-05-13
Updated: 2020-05-13
Packaged: 2021-03-03 05:01:35
Rating: Explicit
Warnings: Rape/Non-Con, Underage
Chapters: 1
Words: 1,067
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24159310
Author URL: https://archiveofourown.org/users/SinningfortheWinning/pseuds/SinningfortheWinning
Summary: Mabel learns her place when she ignores Dipper's warnings about the full moon.
Relationships: Dipper Pines/Mabel Pines
Comments: 5
Kudos: 130





	Full Moon

**Author's Note:**

> If you have requests involving Dipper and Mabel (or GravityFalls characters in general) fucking each other I'm happy to listen to them. Most kinks welcome.

Dipper has tried to tell Mabel to stay away from him during full moons. He had been bitten by a werewolf a few years back during summer at the Mystery Shack and now at sixteen he would change into a big, furry, super horny beast.

Their parents worked a lot and travelled when they weren't working so they never question Dipper locking himself up for a day or two. But Mabel does.

She worries even though Dipper tells her not to and tries to bug him every time he locks himself up in his room.

This full moon she's not so lucky and actually manages to get inside.

At first she's in shock, confused and backing away slowly. But then she screams when Dipper's large wolf form moves too fast for her and closes then locks the door.

He pins her to the ground, one clawed hand on her head and the other ripping her pants off. She smelled so good. Her body would make for a good cock sleeve to breed with.

Mabel yelps when Dipper lifted her hips. He's ripped through her pants and undies and can see her pussy. His large tongue swipes over it aggressively, her clit twitching each time he licked it. Dipper pushes his tongue inside of her and its heaven.

Hot, tight, wet heaven. His massive wolf cock twitches and he sits up.

"Dipper, oh my god no, that's not going to fit! Dipper please!" Mabel can feel the tip at her pussy lips and it's the size of her damn fist! "Oh my god oh my god! I'm going to die! You'll kill me with that thing!"

His mate's pleas are nothing to Dipper. He just needs to get his cock in her and then she'll be fine. He gives a hard push and it only moves Mabel forward. Dipper huffs, moving his paws on the sides of her hips. With them in place to hold her he tries again. His twin is groaning, her pussy trying desperately to stretch enough for his cock.

She's crying and trying to kick her legs when the head of his dick finally popped into her. Mabel cries out and the scent of blood fills the room. She was probably a virgin before this.

With the ability to push forward, Dipper howled then shoved his hips forward as hard as he could. With no other choice, Mabel's cunt and cervix open up and Dipper's cock slides deeper than anything should ever go into his twin.

Mabel is either passed out or unable to move because when Dipper starts fucking her like a wild beast, the teenager lays there and just takes it. Her body is limp and all she can do is breathe heavily while her twin pounds into her without an ounce of mercy.

Dipper is panting and can hardly focus on anything other than the wet slapping sounds of his hips smacking into his sister's ass. He had told her to stay away. She should've listened. Now she was going to spend the entire full moon on his cock.

His first load of the night is coming fast and he's sure Mabel can feel his knot swelling.

"No! Dipper please! Don't cum in me oh my god oh fuck! You can't do this!"

Dipper snarls when she tries to move her hips away and fucks harder. She still tries to move away though so he puts her head in his mouth as a warning.

"Dipper please I know you're in there!"

When his orgasm beings to roll over him Dipper shoves his knot into Mabel, his twin screaming in pain as hot, potent cum floods her fertile womb.

Spurt after spurt her womb fills and Dipper licks the side of her face. His mate was surely bred now, but he would have to keep going to be sure.

"Dipper, it hurts," Mabel whines. She tried to move her hips but Dipper's large knot doesn't allow it.

It's so big in fact that when Dipper decides to move to the bed his twin is lifted off the floor, stuck on his cock. His wolf form is big enough that she has to scramble to put her hands and knees on the floor to keep the knot from pulling on her pussy too much.

Dipper jumps up on the bed and his twin is forced into an odd position, bent from not being able to adjust herself when he jumped. Now he's licking the fur above his cock letting his tongue lap at her back. His mate needs more cum in her womb. Of that his body is sure.

Mabel let's out a horrible scream when Dipper rips his knot out and to shut her up he shoves his tongue into her mouth. He keeps it there as a gag while he moves her into a mating position again, forcing his cock back into her gaping pussy.

His twin screams around his tongue, thrashing under him. Maybe it was too much for a human to mate with him. But his body didn't really care, it only knew that he needed to stuff something or someone full of cum.

Dipper thrusts into Mabel so hard that the bed is groaning. He growled when his second orgasm approaches, no longer caring that Mabel is clawing at the bed for freedom. Her cries are silent now, body too thoroughly fucked to allow any noise to escape.

When his knot finally rams into her again Dipper howls and unleashes the torrent of cum into his sister. Her belly swells and she's screaming for relief, only to find none.

Over and over again during the night he breeds her, Mabel eventually giving up on fighting. She's laying by his side, limp and stuffed to the brim with cum when he turns back into his human form. Maybe he should have felt bad but if she had just listened, she wouldn't be here.

Still horny, Dipper gets up and positions his human cock in front of her face. His twin opens her mouth, a little cough escaping as her tongue rolls out. She's not fighting being fucked even in his human form. Dipper places the tip of his cock on her tongue and slowly slides it forward until he's in her throat, pelvic bone pressing hard against her nose.

Maybe it was a good thing that she didn't listen.

**Author's Note:**

> Mabel knows to listen now.
> 
> Let me know about those requests


End file.
